Update DOMTokenList IDL to current DOM spec (#3545); r=Ms2ger

Ref. whatwg/dom@cb85ac4

Also add [CEReactions]s to DOMTokenList's members.

Author: zcorpan

dom/interfaces.html

@@ -547,14 +547,13 @@ <h1>DOM IDL tests</h1>
   readonly attribute unsigned long length;
   getter DOMString? item(unsigned long index);
   boolean contains(DOMString token);
-  void add(DOMString... tokens);
-  void remove(DOMString... tokens);
-  boolean toggle(DOMString token, optional boolean force);
-  void replace(DOMString token, DOMString newToken);
+  [CEReactions] void add(DOMString... tokens);
+  [CEReactions] void remove(DOMString... tokens);
+  [CEReactions] boolean toggle(DOMString token, optional boolean force);
+  [CEReactions] void replace(DOMString token, DOMString newToken);
   boolean supports(DOMString token);
-           attribute DOMString value;
-  stringifier;
-//  iterable<DOMString>;
+  [CEReactions] stringifier attribute DOMString value;
+  //  iterable<DOMString>;
 };
 </script>
 <script>

html/dom/interfaces.html

@@ -463,14 +463,13 @@ <h1>HTML IDL tests</h1>
   readonly attribute unsigned long length;
   getter DOMString? item(unsigned long index);
   boolean contains(DOMString token);
-  void add(DOMString... tokens);
-  void remove(DOMString... tokens);
-  boolean toggle(DOMString token, optional boolean force);
-  void replace(DOMString token, DOMString newToken);
+  [CEReactions] void add(DOMString... tokens);
+  [CEReactions] void remove(DOMString... tokens);
+  [CEReactions] boolean toggle(DOMString token, optional boolean force);
+  [CEReactions] void replace(DOMString token, DOMString newToken);
   boolean supports(DOMString token);
-           attribute DOMString value;
-  stringifier;
-//  iterable<DOMString>;
+  [CEReactions] stringifier attribute DOMString value;
+  //  iterable<DOMString>;
 };</script>
 <!-- UI Events IDLs -->
 <script type=text/plain class=untested>